Low-frequency variability enhancement of the midlatitude climate in an eddy-resolving coupled ocean–atmosphere model. Part I: anatomy
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Published version
Author(s)
Kurashina, Ryosuke
Berloff, Pavel
Type
Journal Article
Abstract
This study investigated the coupling of the wind-driven ocean gyres with the atmospheric westerly jet using an idealised, eddy-resolving, coupled model. An empirical orthogonal function analysis of the low-pass filtered data showed that the ocean gyre variability is dominated by meridional shifts of the western boundary current extension (WBCE) and changes in the strength of the subtropical inertial recirculation zone. On the other hand, the atmospheric potential vorticity (PV) variability is dominated by the growth of standing Rossby wave patterns, while its pressure variability is dominated by a zonally-asymmetric meridional shift of the atmospheric jet. Damping sea surface temperature (SST) variability in the atmosphere was shown to weaken its PV variability and reduce the zonal asymmetry of the jet-shift mode. Singular value decompositions revealed a positive feedback between meridional shifts of the WBCE and the growth of standing Rossby wave disturbances in the atmospheric jet. The atmosphere’s response is controlled by shifts in the meridional eddy heat flux over the SST front which triggers the growth of baroclinic instabilities. This instability growth eventually leads to a large-scale, barotropic pressure response over the eastern ocean basin, or an aforementioned meridional shift of the atmospheric jet. Reduction in the atmospheric resolution inhibits the ability of atmospheric eddies to resolve length scales associated with meridional shifts of the SST front and WBCE. The lack of resolution consequently weakens the influence of ocean gyre variability on the atmospheric jet and reduces the strength of the positive feedback.
Date Issued
2023-08
Date Acceptance
2023-04-05
Citation
Climate Dynamics, 2023, 61 (3-4), pp.1997-2023
ISSN
0930-7575
Publisher
Springer
Start Page
1997
End Page
2023
Journal / Book Title
Climate Dynamics
Volume
61
Issue
3-4
Copyright Statement
© Crown 2023, corrected publication 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Identifier
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000972795700001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=a2bf6146997ec60c407a63945d4e92bb
Subjects
DECADAL VARIABILITY
DRIVEN
DYNAMICS
GULF-STREAM
KUROSHIO EXTENSION
LARGE-SCALE
MERIDIONAL SHIFTS
Meteorology & Atmospheric Sciences
NORTH PACIFIC
Physical Sciences
ROSSBY WAVES
Science & Technology
SST ANOMALIES
Publication Status
Published
Date Publish Online
2023-04-20